A marine aims an RPG-7, a portable rocket- propelled grenade launcher, during military exercises conducted by the Russian Pacific Fleet' s naval infantry unit at the Bamburovo firing range on February 2, 2017. The drills are a part of preparations for the Suvorov Attack and Sniper Line army competitions. (Photo by Yuri Smityuk/TASS)

Young African lion Asali (R) jumps for a bungee-ball toy as her father Jambo or “Bruiser” looks on at the opening of a savannah-themed makeover of the lion enclosure at Taronga Zoo August 29, 2006 in Sydney, Australia. The renovation includes sandstone rock features, a wading pool, and red ochre crushed granite substrate in a move to make the enclosure more closely resemble the natural habitat of the African savannah. (Photo by Ian Waldie/Getty Images)

A videographer uses a drone as he takes a video of a model presenting a lingerie creation at the rehearsal for Eve's Temptation collection during China Fashion Week in Beijing, October 26, 2014. (Photo by Kim Kyung-Hoon/Reuters)

Iraqi Kurdish female fighter Haseba Nauzad looks through a pair of binoculars during a deployment near the frontline of the fight against Islamic State militants in Nawaran near Mosul, Iraq, April 20, 2016. (Photo by Ahmed Jadallah/Reuters)

A workman sweeping the highest sidewalk in the world, the 81st story of the Empire State Building, the world's tallest building, to the top of which the greatest dirigible “Los Angeles” will attempt to moor, New York, New York, early 1930s. This photo was made 1,248 feet above street level. (Photo by Adam Glickman/Underwood Archives/Getty Images)

Iranian-Kurdish female fighters hold their weapons during a battle with Islamic State militants in Bashiqa, near Mosul, Iraq on November 3, 2016. (Photo by Ahmed Jadallah/Reuters)

“Monorail Subway, Capitol To Senate. The Car. Senators Swanson And Townsend As Passengers, 1916”. (Photo by Harris & Ewing Collection). (Please click to enlarge)

A Syria Democratic Forces (SDF) fighter comforts a civilian who was evacuated with others by the SDF from an Islamic State-controlled neighbourhood of Manbij, in Aleppo Governorate, Syria, August 12, 2016. The SDF has said Islamic State was using civilians as human shields. (Photo by Rodi Said/Reuters)